[Hallicrafters] Problem with HT-32A

[Al Parker]

Hi Burt,
	Haven't heard from you in ages, sorry it's with a problem now ;-)
	My HT-32 ha a Peter Dahl xfmr too, nice, big, shiny, as you say.  Is 
your doing this on all bands?  How long's it been since it was working 
OK, and what's been done just before it quit?  The steady -49 bias 
voltage, if it's rock steady, would indicate to me that you're not 
getting any drive to the finals.  Mine changes some with a signal.  The 
meter is just an output monitoring meter, not plate current, so with no 
indication there, it says the same.  It won't indicate just a small 
amount of power.  The band switches are prone to getting cruddy with 
lack of use, maybe just exercising it several times from end to end 
would help.
	Do you here any signal at the output freq. when you key it, on CW or 
DSB?  If so, there's probably some signal getting at least to the 
driver, maybe it's bad.  If not, you'll need to look further back.
	That's a little bit to look at & think about,  Let us know what you 
might find as you get into it.
	I've had mine on the air on the Vintage Sideband Net for the last few 
weeks, and Bob, W9RAN, has had his on also.  We've both made an ALC mod. 
that was in a CQ mag "way back", and it seems to be helping keep the 
signal level up, without overdriving.
73,

Al, W8UT
www.boatanchors.org
www.hammarlund.info

"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole

On 3/5/2012 6:35 PM, K4PRF - Burton Pratt wrote:
> This is a beautiful HT-32A with a big shiny Peter Dahl power transformer
> installed a few years back.  It was operating fine but just quit making
> any power.  I have checked all the voltages and tube base resistances.
> All are very close to specks.  I have to admit that I don't understand
> how the transmit keying is accomplished other than through the vox
> relay, cw key or calibrator control.  None of these are keying the
> transmitter.  No motion on the meter.  It is as if the RF power section
> was just turned off.  I think something is killing the bias control of
> the driver and output tubes.  When I try keying the transmitter I can
> hear the relay operate but the grid bias on the 6146s holds at around
> -49 volts.  I know all about the problem with the 5V4s originally used
> in the low voltage supply.  I use 5R4s in this transmitter and in my
> HT-37.  This transmitter is in original condition except for the power
> transformer and the bias diode.  All of the caps are original.  Tubes
> all check good on a TV-7 but I have substituted all with no change.  I
> have not touched the alignment at all .  I'll bet that I am not the only
> person that has run up on this problem so any suggestions will be
> greatly appreciated.
>
> 73,
>
> Burt,  K4PRF